Force compilation error with sealed classes

Question

With sealed classes you can use exhaustive when expressions and omit the else clause when the expression returns a result:

sealed c         


        

Answer 1

Our approach avoids to have the function everywhere when auto-completing. With this solution you also have the when return type in compile time so you can continue using functions of the when return type.

Do exhaustive when (sealedClass) {
  is SealedClass.First -> doSomething()
  is SealedClass.Second -> doSomethingElse()
}

You can define this object like so:

object Do {
    inline infix fun exhaustive(any: T?) = any
}